1. Field of the Invention
The present invention relates to a communication terminal apparatus to be applied to a terminal provided with a wireless communication function, such as a mobile phone terminal apparatus, and also relates a method for supplying a terminal power source, which can be applied to such a communication terminal apparatus. In particular, the present invention relates to a technology for supplying electric power to a terminal apparatus using a contactless charging function.
2. Description of the Related Art
In recent years, a charging apparatus or the like has been provided for supplying electric power to a separate terminal apparatus in a contactless state with no connection of a power-supplying terminal or the like to supply electric power to the inner secondary battery of the terminal apparatus.
Heretofore, an electromagnetic induction system has been known as a system for contactless power transmission. According to such a system, a power-transmitting coil is arranged on an apparatus on a power-transmitting side and a power-receiving coil is arranged on an apparatus on a power-receiving side. Then, the portion of the apparatus on the transmission-side, on which the power-transmitting coil is arranged, is brought near to the portion of the apparatus on the power-receiving side, on which the power-receiving coil is arranged. Thus, these coils are brought into magnetic flux connection to allow them to perform power transmission in a contactless manner.
For example, as shown in FIG. 13, a power-transmitting coil 11 is arranged on a terminal apparatus 10a and a power-receiving coil 12 is arranged on another terminal apparatus 10b. Furthermore, like the state shown in FIG. 13, the power-receiving coil 12 of the terminal apparatus 10b is allowed to receive the electric power from the power-transmitting coil 11 of the terminal apparatus 10a in proximity to each other.
In the terminal apparatus 10b on the power-receiving side, the received power can be provided for charging the inner secondary battery of the terminal apparatus 10b or the operation of the terminal apparatus 10b. 
The electromagnetic method has been known as a technology for contactless power transmission. However, it can transmit electric power only between apparatuses just proximal to each other because of a transmissible range of several millimeters. Therefore, the application of the electromagnetic induction type is limited to some of apparatuses, such as a water-proof type terminal, which is difficult to expose its charging terminal.
In recent years, as an alternative system for effectively supplying electric power to a terminal apparatus located at some distance, a so-called magnetic resonance system has been developed, proceeding toward practical use. In this system, an LC circuit, which includes a coil and a conductor, is installed in each of the power-transmitting side apparatus and the power-receiving side apparatus. A combination of the LC circuits on the respective apparatuses causes resonance of electric field/magnetic field between them to perform wireless transmission of electric power. In order to produce resonance of electric field/magnetic field between their circuits, their frequencies are kept equal to each other.
In the case of the magnetic resonance method, it is possible to attain a short-distance transmission of from about several centimeters to several meters. Furthermore, if there are two or more power-receiving side apparatuses within a power transmittable area, a single apparatus on the power-transmitting side may transmit electric power simultaneously to two or more apparatuses on the power-receiving side.
For example, as shown in FIG. 14, three terminal apparatuses 20a, 20b, and 20c are located in close proximity to one another. The terminal apparatus 20a is provided with a magnetic resonance type power-transmitting coil 21 and the terminal apparatuses 20b and 20c are provided with magnetic resonance type power-transmitting coils 22, respectively. Two terminal apparatuses 20b and 20c are arranged in the power transmissible area Ap of the terminal apparatus 20a. 
Under such conditions, if three terminal apparatuses 20a, 20b, and 20c have the same resonant frequency, the single terminal apparatus 20a sends electric power simultaneously to two terminal apparatuses 20b and 20c. However, each of the terminal apparatuses 20b and 20c can receive almost half the power, compared with one received by a single terminal apparatus.
Japanese Unexamined Patent Application Publication No. 2010-63245 describes the supply of power by a magnetic resonance method in which a power-receiving side is selected from candidate apparatuses with reference to their resonant frequencies.
Japanese Unexamined Patent Application Publication No. 2009-148151 describes the application of contactless charge to a wireless communication terminal apparatus.